1. Field of the Invention
This invention relates to a flame resistant blend of a polyurethane polymer, a chlorinated polyethylene, optionally polyethylene resin, and a flame retardant selected from the group of 1,2,3,4,7,8,9,10,13,13,14,14-dodecachloro-1,4,4a,6a,7,10,10a,12a-octahydro -1,4:7,10-dimethanodibenzocyclooctane (DCCO), 1,2,3,4,5,6,7,8,10,10,11,11-dodecachloro-1,4,4a,4b,5,8,8a,9a-octahydro-1,4 :5,8-dimethanodibenzofuran (DCOB), 6-(1',4',5',6',7',7'-hexachloronorborn-5'-en-2'-yl)-1,2,3,4,10,10-hexachlo ro-1,4,4a,5,6,7,8,8a-octahydro-1,4:5,8-dimethanonaphthalene (DCDN), and 6-(1',4',5',6',7',7'-hexachloronorborn-5'-en-2'-yl)-1,2,3,4,10,10-hexachlo ro-1,4,4a,5,6,7,8,8a-octahydro-1,4-methanonaphthalene (DCMN). Also antimony oxide may be included to reduce the amount of retardant necessary.
Chemical structures of these flame retardants are as follows: ##SPC1##
2. Description of the Prior Art
Some of the flame retardants used herein have been heretofore used with a variety of other polymers, including polypropylene, polyvinyl chloride, etc. Some have also been said to be useful for polyurethanes, though no specific examples of such have been shown and no use in a polyurethane-chlorinated polyethylene blend has been shown at all. See U.S. Pat. Nos. 3,382,204; 3,385,819; 3,392,136; 3,396,201 and 3,403,036 as well as German OS No. 2,153,101. Moreover, all of these references require the use of very high loadings of the flame retardants in order to produce the retardancy. The blends of the present invention require no more than 25 pph. of total flame retardant with or without antimony trioxide. Additionally, the physical properties of the flame resistant samples of the references are decidedly inferior to those of the non-flame resistant samples therein. On the contrary in this invention, the physical properties of the flame resistant blends are almost identical with those of the non-flame-resistant blends.